| 摘要 |
<p>The block (1) has spacing units (4) arranged on longitudinal and transversal edges (2, 3) of the block. Spacers (5) are arranged in a median vertical axis of the spacing units. The spacers have shape of half-truncated cone or half-truncated pyramid. A large base of the spacers extends at the level of a polygonal base of the spacing units. Each spacer cooperates with a vertical recess (6) provided in an edge of the block, where a section of the spacer is equal to that of the large base of the spacer and constant over entire height of the block.</p> |
